【问题】Java用Long类型, 导致前端js精度丢失

1.

后端在对象的属性上加注解@JsonSerialize(using = ToStringSerializer.class)即可

2 推荐

@EnableWebMvc
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {


    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("doc.html").addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
    }

    /**
     * 避免Long类型返回前端导致精度丢失的问题
     * @param converters
     */
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        MappingJackson2HttpMessageConverter jackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();

        ObjectMapper objectMapper = new ObjectMapper();
        /**
         * 序列换成json时,将所有的long变成string
         * 因为js中得数字类型不能包含所有的java long值
         */
        SimpleModule simpleModule = new SimpleModule();
        simpleModule.addSerializer(Long.class, ToStringSerializer.instance);
        simpleModule.addSerializer(Long.TYPE, ToStringSerializer.instance);
        objectMapper.registerModule(simpleModule);

        jackson2HttpMessageConverter.setObjectMapper(objectMapper);
        converters.add(jackson2HttpMessageConverter);
    }



}

3.配置文件增加

Jackson有个配置参数​​WRITE_NUMBERS_AS_STRINGS​​​，可以强制将所有数字全部转成字符串输出。其功能介绍为：​​Feature that forces all Java numbers to be written as JSON strings.​​。使用方法很简单，只需要配置参数即可：

spring:
  jackson:
    generator:
      write_numbers_as_strings: true